TWI782096B - Conductive paste and method for producing ceramic electronic component - Google Patents

Abstract

(X/Y)。 Provides a conductive paste capable of forming a conductive film with excellent adhesion to substrates. According to the present invention, there is provided a conductive paste for forming a conductive film containing an inorganic component and an organic component. The said inorganic component contains electroconductive powder. The above-mentioned organic component contains an organic binder and a rosin-based resin. The above-mentioned rosin-based resin contains an acid-valued rosin having an acid value. When the acid value amount of the above-mentioned acid value rosin per unit mass of the above-mentioned conductive paste is represented as X (mgKOH), and the content of the above-mentioned inorganic component per unit mass of the above-mentioned conductive paste is represented as Y (g), the above-mentioned X and the above Y satisfy the following formula: 0.8

(X/Y).

Description

Conductive paste and method for producing ceramic electronic component

The present invention relates to a conductive paste. In particular, it relates to a conductive paste suitable for forming internal electrode layers of laminated ceramic electronic components.

In the manufacture of electronic components such as multi-layer ceramic capacitors (Multi-Layer Ceramic Capacitor: MLCC), the method of applying a conductive paste to a substrate to form a conductive film and firing it to form an electrode layer is widely used (see patent Literature 1~4).

In one example of the manufacturing method of MLCC, first, a plurality of unfired ceramic green sheets containing ceramic powder and a binder are prepared. Next, a conductive paste is applied to each of the plurality of ceramic green sheets and dried to form a conductive film. Next, a plurality of ceramic green sheets with conductor films are stacked, and pressure is applied in the stacking direction so as to be pressed against each other. Next, it is cut to a predetermined size, and then fired and integrally sintered. Next, external electrodes are formed on both end surfaces of the fired composite. As described above, an MLCC having a structure in which a plurality of dielectric layers mainly composed of ceramics and internal electrode layers formed of baked bodies of conductive paste are alternately laminated is produced.

For example, Patent Document 1 discloses an internal electrode of an MLCC that contains conductive powder, a resin binder, and a solvent as the main components, and the resin binder contains ethyl cellulose-based resin and a resin with good adhesion to ceramic green sheets. for layer formation conductive paste. According to the conductive paste of Patent Document 1, during the pressurization, the adhesiveness between the ceramic green sheet and the conductor film is improved, and the conductor film can be suppressed from being deviated from a predetermined position (position shift).

[Prior art literature]

[Patent Document]

Patent Document 1: Japanese Patent Application Publication No. 2004-186339

Patent Document 2: Japanese Patent Application Publication No. 2009-147359

Patent Document 3: Japanese Patent Application Publication No. 2011-139019

Patent Document 4: Japanese Patent Application Publication No. 2012-129181

However, according to the studies of the inventors of the present invention, room for improvement has been found in the conductive paste described in Patent Document 1. That is, for conventional conductive pastes, for example, from the standpoint of productivity improvement and cost reduction, shortening the pressurization time or lowering the pressurization pressure at the time of crimping cannot obtain a sufficient effect of improving the adhesiveness. There may be a positional deviation. Therefore, users have requested to form a conductor film with better adhesion to a base material (for example, a ceramic green sheet).

The present invention has been made in view of the above problems, and an object of the present invention is to provide a conductive paste capable of forming a conductive film having excellent adhesion to a base material.

(X/Y)。 According to the present invention, there is provided a conductive paste for forming a conductive film containing an inorganic component and an organic component. The said inorganic component contains electroconductive powder. The above-mentioned organic component contains an organic binder and a rosin-based resin. The above-mentioned rosin-based resin contains an acid-valued rosin having an acid value. When the acid value amount of the above-mentioned acid value rosin per unit mass of the above-mentioned conductive paste is represented as X (mgKOH), and the content of the above-mentioned inorganic component per unit mass of the above-mentioned conductive paste is represented as Y (g), the above-mentioned X and the above Y satisfy the following formula: 0.8

(X/Y).

According to the above-mentioned technical features, the acidic groups of the rosin-based resin act appropriately on the surface of the inorganic component to improve the viscosity and fluidity of the conductor film. Therefore, according to this conductive paste, it is possible to form a conductor film excellent in adhesion to a base material (for example, a ceramic green sheet).

In addition, "acid value" means the content (mg) of potassium hydroxide (KOH) required to neutralize the free fatty acid contained in the unit sample (1g). The unit is mgKOH/g.

In addition, for each unit mass (100g) of the conductive paste, "acid value X (mgKOH) of rosin with acid value" can be expressed by the following formula (1): X (mgKOH) = acid value of rosin with acid value Calculated by (mgKOH/g)×the content ratio (mass %) of rosin having an acid value based on the whole conductive paste. As the acid value of the above-mentioned rosin having an acid value, a value measured by a potentiometric titration method based on JIS K0070:1992 can be used.

In addition, for each unit mass (100g) of the conductive paste, the "inorganic component content Y (g)" can be expressed by the following formula (2): Y (g) = Σ[Based on the whole conductive paste The content ratio (mass %)] of each inorganic component of ] is calculated.

3。由此可以合適地實現表面平滑性優異的導體膜。 In a preferred mode disclosed herein, the above-mentioned X/Y satisfies the following formula: (X/Y)

3. Thereby, a conductor film excellent in surface smoothness can be suitably realized.

In a preferred aspect disclosed herein, the acid value of the above-mentioned rosin having an acid value is 100 mgKOH/g or more. Thereby, the effect of the technology disclosed here can be suitably achieved while suppressing the usage-amount of the rosin which has an acid value.

In a preferred aspect disclosed here, the rosin-based resin is 2% by mass or less when the entire conductive paste is 100% by mass. Thereby, the rosin-based resin is less likely to remain in the electrode layer after firing, and an electrode layer excellent in conductivity and density can be suitably realized.

In a preferred aspect disclosed herein, the conductive powder is at least one of nickel, platinum, palladium, silver, and copper. Thereby, an electrode layer excellent in electrical conductivity can be realized suitably.

In a preferable aspect disclosed here, it is used to form an internal electrode layer of a laminated ceramic electronic component. For example, in chip-type multilayer ceramic capacitors, the thickness of each layer of the dielectric layer and the internal electrode layer is reduced to a sub-micron to micron level, and the number of stacked layers exceeds 1,000. When manufacturing such a laminated ceramic electronic component having a multilayer structure, problems due to misalignment tend to occur. Therefore, the above-mentioned conductive paste can be suitably used in the formation of the internal electrode layer of the laminated ceramic electronic component.

10:Laminated ceramic capacitors

20: Dielectric layer

30: Internal electrode layer

40: External electrode

FIG. 1 is a cross-sectional view schematically showing a multilayer ceramic capacitor according to one embodiment.

Fig. 2 is a graph showing the relationship between X/Y and peel strength.

Preferred embodiments of the present invention will be described below. It should be noted that matters (such as the production method of the conductive paste, the formation method of the conductive film, etc.) other than the matters particularly mentioned in this specification (such as the composition of the conductive paste) required for implementing the present invention can be It is a matter of design for those skilled in the art based on prior art in this field. The present invention can be implemented based on the contents disclosed in this specification and common technical knowledge in this field.

In the following description, the conductive paste is applied to the substrate, and the film before firing is obtained by drying at a temperature (for example, 100° C. or lower) of the boiling point of the dispersant contained in the conductive paste. The shape is called "conductor film". In addition, description of "A to B" which shows a range in this specification means A or more and B or less.

"Conductive Paste"

The conductive paste (hereinafter sometimes simply referred to as "paste") disclosed here is used for the formation of a conductor film. In addition, in this specification, a "paste" is a term including a composition, an ink, and a slurry. The components of the conductive paste disclosed here are roughly divided into inorganic components (A) and organic components (B). Each component will be described in order below.

《Inorganic Components (A)》

The inorganic component (A) is typically a component that does not burn out during firing of the conductive film and remains after firing to constitute the electrode layer. The inorganic component (A) contains at least electroconductive powder (A-1).

<(A-1) Conductive powder>

The conductive powder (A-1) is a component that imparts conductivity to the electrode layer. The type and the like of the conductive powder (A-1) are not particularly limited, and one type or two or more types can be appropriately used from various types of conductive powders generally used depending on the application or the like. As a preferable example of electroconductive powder (A-1), electroconductive metal powder is mentioned. Specifically, nickel (Ni), platinum (Pt), palladium (Pd), gold (Au), silver (Ag), copper (Cu), ruthenium (Ru), rhodium (Rh), iridium (Ir ), osmium (Os), aluminum (Al) and other metals, and their mixtures, alloys, etc.

Although not particularly limited, for example, for forming an internal electrode layer of a laminated ceramic electronic component, it is preferable to use a metal species whose melting temperature of the conductive powder (A-1) is sufficiently higher than the sintering temperature of the ceramic powder contained in the dielectric layer. Examples of such metal species include nickel, platinum, palladium, silver, and copper, and among them, nickel is preferable from the viewpoint of being inexpensive and having an excellent balance between conductivity and cost.

The properties of the particles constituting the conductive powder (A-1), such as the size and shape of the particles, are not particularly limited as long as they satisfy the minimum dimension in the cross section of the electrode layer (typically, the thickness and/or width of the electrode layer). .

The average particle diameter of the conductive powder (A-1) (corresponding to the cumulative particle diameter of 50% from the smaller particle diameter side in the particle size distribution based on the number of particles observed by electron microscope observation. The same applies below) can be determined according to the use of the paste, for example. , the size (fineness) of the electrode layer, etc. are appropriately selected. Usually, the average particle diameter of the conductive powder (A-1) is about several nm to several tens of μm, for example, preferably 10 nm to 10 μm.

As an example, in the application of forming the internal electrode layer of an ultra-small MLCC, the average particle diameter of the conductive powder (A-1) is smaller than the thickness of the internal electrode layer (the thickness of the stacking direction Length) is small, typically 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.25 μm or less. When the average particle diameter is equal to or less than a predetermined value, a thin film-shaped conductor film can be stably formed. Furthermore, the arithmetic mean roughness Ra of the conductor film is remarkably small, for example, can be suppressed to a level of 5 nm or less. In addition, generally, when the arithmetic mean roughness Ra of the conductor film is small, the above-mentioned problem of "positional deviation" tends to occur. Therefore, the technical effect disclosed here is exerted immediately.

The average particle diameter of the conductive powder (A-1) is approximately 0.01 μm or more, typically 0.05 μm or more, preferably 0.1 μm or more, for example 0.2 μm or more. When the average particle diameter is equal to or larger than a predetermined value, the surface energy of the particles is suppressed, and aggregation in the paste is suppressed. Therefore, an electrode layer with high conductivity and high density can be realized suitably. Moreover, self-leveling property can be improved more favorably.

The specific surface area of the conductive powder (A-1) (the BET specific surface area measured by the nitrogen adsorption method and analyzed by the BET method. The same applies hereinafter) is not particularly limited, but is approximately 10 m ² /g or less, preferably 1 to 8 m ² /g. g. For example, 2~6m ² /g is suitable. Thereby, aggregation in the paste is appropriately suppressed, and the uniformity, dispersibility, and storage stability of the paste can be improved more favorably. In addition, an electrode layer having excellent electrical conductivity can be realized more stably.

The shape of the conductive powder (A-1) is not particularly limited, but it is preferably a true spherical shape or a substantially spherical shape. That is, the average aspect ratio of the conductive powder (A-1) (the average value of the ratio of the major axis to the minor axis of the particles calculated based on electron microscope observation) is typically 1 to 2, preferably 1 to 1.5. should. Thereby, the viscosity of the paste can be kept low, and the handleability of the paste and the workability at the time of film formation can be improved. In addition, the uniformity of the paste can also be improved.

The content ratio of the conductive powder (A-1) is not particularly limited, but when the entire paste is 100% by mass, it is approximately 30% by mass or more, typically 40 to 95% by mass, for example, 45 to 60% by mass It is appropriate. By satisfying the above range, it is possible to suitably realize a highly conductive and dense electrode layer. In addition, the handleability of the paste and the workability at the time of film formation can be improved.

In addition, the inorganic component (A) may consist only of electroconductive powder (A-1), and may contain various inorganic additives other than electroconductive powder (A-1) as needed. As the inorganic additive, known inorganic additives that can be used in common conductive pastes can be appropriately used as long as the technical effect disclosed here is not significantly impaired. Examples of inorganic additives include dielectric powder (A-2), sintering aids, inorganic fillers, and the like. For example, when forming an internal electrode layer of a laminated ceramic electronic component, it is preferable to contain a dielectric powder (A-2) as an inorganic additive in addition to the conductive powder (A-1).

<(A-2) Dielectric Powder>

The dielectric powder (A-2) is a component that relaxes the thermal shrinkage of the conductive powder (A-1) during firing of the conductive film. The type and the like of the dielectric powder (A-2) are not particularly limited, and one type or two or more types can be appropriately used according to the application among various inorganic material powders generally used. As a preferable example of the dielectric powder (A-2), _ABO3 Shown are ceramics, titania, titania, etc. with a perovskite structure. For example, when forming an internal electrode layer of a laminated ceramic electronic component, it is preferable to use the same type of material as the ceramic powder contained in the dielectric layer, typically barium titanate (BaTiO ₃ ). As a result, the integrity of the dielectric layer and the internal electrode layer is further improved.

The relative dielectric constant of the dielectric powder (A-2) is typically 100 or higher, preferably 1,000 or higher, for example, about 1,000 to 20,000.

The properties of the particles constituting the dielectric powder (A-2), such as the size and shape of the particles, are not particularly limited as long as they satisfy the minimum dimension in the cross section of the electrode layer (typically, the thickness and/or width of the electrode layer).

The average particle diameter of the dielectric powder (A-2) can be appropriately selected according to the use of the paste, the size (fineness) of the electrode layer, and the like, for example. Usually, the average particle size of the dielectric powder (A-2) is approximately several nm to several tens of μm, typically 0.01 μm to 10 μm, preferably 0.3 μm or less, for example 0.05 μm or less. From the viewpoint of improving the conductivity, uniformity, and compactness of the electrode layer, the average particle size of the dielectric powder (A-2) is preferably smaller than that of the conductive powder (A-1), and the conductive powder is more preferably About 1/20~1/2 of the average particle diameter of (A-1).

As an example, in the application of forming an internal electrode layer of an ultra-small MLCC, the average particle size of the dielectric powder (A-2) is preferably about a few nm to several hundreds of nm, for example, 10 to 100 nm. When the average particle diameter is equal to or larger than a predetermined value, the surface energy of the particles is suppressed, and aggregation in the paste is suppressed. Therefore, self-leveling properties can be improved more favorably. In addition, the arithmetic average roughness Ra of the conductor film can be suppressed to be remarkably small as long as the average particle diameter is not more than a predetermined value.

The specific surface area of the dielectric powder (A-2) is not particularly limited, but is typically larger than the specific surface area of the conductive powder (A-1), approximately 100 m ² /g or less, preferably 5 to 80 m ² /g, for example, 10 ~70m ² /g is suitable. Thereby, the aggregation of the particles is appropriately suppressed, and the uniformity, dispersibility, and storage stability of the paste can be improved more favorably. In addition, an electrode layer having excellent electrical conductivity can be realized more stably.

When the paste contains the dielectric powder (A-2), the content ratio of the dielectric powder (A-2) is not particularly limited. When it is 100% by mass, it is preferably about 1 to 20% by mass, typically 3 to 15% by mass, for example, 5 to 10% by mass. By satisfying the said range, the effect of a dielectric powder (A-2) can be exhibited suitably, and the heat shrinkage of an electroconductive powder (A-1) can be moderated more favorably. In addition, an electrode layer excellent in conductivity can be realized suitably.

The content ratio of the inorganic component (A) in the paste is not particularly limited, but from the viewpoint of improving the handling properties of the paste, the workability during film formation, and the viewpoint of improving the conductivity and density of the electrode layer, the When the whole paste is 100% by mass, it is approximately 30 to 95% by mass, typically 40 to 70% by mass, for example, 50 to 65% by mass.

《Organic Ingredients (B)》

The organic component (B) is typically a component that burns out during firing of the conductor film (for example, heat treatment at a temperature of about 250° C. or higher, for example, 500° C. or higher in an oxidizing atmosphere). That is, the organic component (B) preferably has a boiling point lower than the firing temperature of the conductor film. The organic component (B) contains at least an organic binder (B-1) and a rosin-based resin (B-2).

<(B-1) Organic binder>

The organic binder (B-1) imparts adhesiveness to the conductor film before firing, and makes the inorganic Between the components (A) and between the conductive film and the base material supporting it is a component that adheres closely. The organic binder (B-1) is preferably compatible with the rosin-based resin (B-2) described later. The organic binder (B-1) is typically an organic polymer (polymer) having a repeating structural unit. The type and the like of the organic binder (B-1) are not particularly limited, and one or two or more kinds can be appropriately used from among various organic polymers generally used depending on the application or the like. As a preferable example of the organic binder (B-1), organic polymer compounds other than rosin-based resins (B-2) described later, such as cellulose-based resins, butyral-based resins, acrylic resins, Epoxy resin, phenolic resin, alkyd resin, vinyl resin, etc. Among these, cellulose-based resins are preferred from the viewpoint of excellent combustion and decomposability during firing, the viewpoint of environmental consideration, and the like.

Examples of cellulose-based resins include, for example, a part or all of the hydrogen atoms in the hydroxyl group of cellulose, which is a repeating structural unit, replaced by an alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an acetyl group, etc. Cellulose organic acid esters (cellulose derivatives) substituted with allyl groups such as , propionyl, butyryl, hydroxymethyl, hydroxyethyl, carboxymethyl, carboxyethyl, etc. Specific examples include methylcellulose, ethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, Carboxyethyl cellulose, carboxyethyl methyl cellulose, cellulose acetate phthalate, nitrocellulose, etc.

Examples of butyral-based resins include homopolymers (homopolymer) of vinyl acetate, vinyl acetate as a main monomer (a component accounting for 50% by mass or more of all monomers, the same applies hereinafter) and containing A copolymer of auxiliary monomers whose main monomers are copolymerizable. Examples of homopolymers include polyethylene Alcohol butyral. Specific examples of copolymers include polyvinyl alcohol whose main chain skeleton contains vinyl butyral (butyral group), vinyl acetate (acetyl group), and vinyl alcohol (hydroxyl group) as repeating structural units. Butyral (PVB), etc.

Examples of acrylic resins include homopolymers of alkyl (meth)acrylates, those containing alkyl (meth)acrylates as main monomers and auxiliary monomers copolymerizable with the main monomers. copolymer. Specific examples of the homopolymer include, for example, polymethyl(meth)acrylate, polyethyl(meth)acrylate, polybutyl(meth)acrylate, and the like. As a specific example of a copolymer, the block copolymer etc. which contain the polymer block of a methacrylate and the polymer block of an acrylate as a structural unit are mentioned, for example. In addition, in this specification, "(meth)acrylate" means the term of acrylate and methacrylate.

The weight-average molecular weight Mw of the organic binder (B-1) (measured by gel chromatography (Gel Permeation Chromatography: GPC) and converted to a weight-based average molecular weight using a standard polystyrene calibration curve. The same applies hereinafter) is approximately 2 More than 10,000, typically 20,000 to 1 million, for example, 50,000 to 500,000 is suitable. When the molecular weight is more than a predetermined value, the adhesiveness of the organic binder (B-1) increases, and the adhesive effect can be exhibited with a small amount of addition. Moreover, if the molecular weight is below a predetermined value, the viscosity of the paste can be kept low, and the handleability and self-leveling properties of the paste can be improved. Accordingly, unevenness on the surface of the conductor film can be suppressed to be smaller.

The content ratio of the organic binder (B-1) is not particularly limited, but it is approximately 0.1 to 10% by mass, typically 0.5 to 5% by mass, for example, 1 to 3% by mass when the entire paste is 100% by mass. % is appropriate. By satisfying the above range, it is possible to improve The workability of the paste and the workability of the film formation are highly suppressed from delamination. In addition, self-leveling properties can be improved to realize a smoother surface conductor film.

<(B-2) Rosin-based resin>

The rosin-based resin (B-2) is a so-called tackifier. An example is a pressure sensitive adhesive. Rosin-based resin (B-2) is used to improve the viscosity (adhesion to the substrate), fluidity, and wettability (affinity) of the conductor film before firing, and to improve the conductivity of the conductor film and its support. Adhesive component of the substrate. For example, in the application of forming the internal electrode layer of a laminated ceramic electronic component, it is a component which improves the adhesiveness of a conductor film and the ceramic green sheet which supports it.

The rosin-based resin (B-2) contains rosin and its derivatives. Rosin is a nonvolatile component of pine resin contained in plants of the Pinaceae family. Rosin includes tall rosin, gum rosin and wood rosin. Examples of derivatives of rosin include polymerized rosin, modified rosin, disproportionated rosin, hydrogenated rosin, hydrogenated rosin, maleated rosin, fumarated rosin, acrylated rosin, phenolic modified rosin, ESTER GUM, and their esters, etc. Esterification of rosin can use polyhydric alcohols, such as ethylene glycol, diethylene glycol, glycerin, pentaerythritol, for example.

Rosin-based resins (B-2) contain tricyclic diterpene isomers with 20 carbon atoms called resin acids, such as abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, One or more kinds of hydroabietic acid are used as main components (components accounting for more than 50 mol%). The rosin-based resin (B-2) typically mainly contains abietic acid (the component accounting for the largest ratio on a molar basis). Abietic acid has a bulky ring structure (phenanthrene skeleton) with high hydrophobicity and a hydrophilic carboxyl group.

Examples of commercially available rosin-based resins (B-2) include Arakawa Chemical Co., Ltd. White chrysanthemum rosin, ARDYME (registered trademark) R-140, R-95, Malkyd (registered trademark) No.1, 2, 5, 6, 8, 31, 32, 33, 32-30WS, 3002, TRAFFICS from Kogyo Co., Ltd. (registered trademark) 4102, ESTER GUM 105, AT, H, HP, Pencel (registered trademark) GA-100, AZ, C, D-125, D-135, D-160, KK, SUPER ESTER L, A-18 , A-75, A-100, A-115, A-125, RONDIS (registered trademark) R-CH, K-25, K-80, N-18, Pinecrystal (registered trademark) KR-85, KR-612 , KR-614, KE-604, KR-120, KR-140, KR-50M, Highpale (registered trademark) CH, etc., Neotoll (registered trademark) G2 of Harima Chemicals Group, Inc., 101N, 125HK, HARITACK 8LJA, ER95,SE10,PH,F85,F105,FK100,FK125,PCJ,4851,4821,4740,28JA,F-75,FG-90,AQ-90A,HARIMAX T-80,R-100,M-453,R -80, HARIESTER TF, S, KT-3, C, DS-70L, DS-90, DS-130, AD-130, MSR-4, etc.

The weight-average molecular weight Mw of the rosin-based resin (B-2) is typically smaller than that of the organic binder (B-1), and is approximately less than 10,000, for example, several hundred to several thousand.

The softening point of the rosin-based resin (B-2) by the ring and ball method is approximately 60 to 250°C, typically 70 to 200°C, for example, preferably 80 to 185°C. When the softening point is within the above range, the adhesiveness and wettability of the conductor film can be exhibited stably at a higher level.

The rosin-based resin (B-2) may be in the form of solid (powder) or liquid, or may be in the form of an emulsion dispersed in a solvent.

The rosin-based resin (B-2) contains an acid-value rosin having an acid value (the acid value exceeds the lower limit of detection). Rosin having an acid value is a component for adjusting the acid value amount X per unit mass of the paste. Acid value rosin has 1 or 2 or more acidic groups. Koh pine Perfume typically has one or more carboxyl groups (COOH groups) as acidic groups. Rosin with acid value can replace the carboxyl group or have one or more hydroxyl groups (OH groups) as acid groups in addition to the carboxyl group. The acid value of rosin with acid value is about 10 mgKOH/g or more, typically 40 mgKOH /g or more, for example, 50 mgKOH/g or more, preferably 100 mgKOH/g or more. Thereby, the usage-amount of the rosin which has an acid value can be suppressed and an adhesive effect can be exhibited suitably. Therefore, an electrode layer with high conductivity and high density can be realized suitably.

The upper limit of the acid value of rosin with an acid value is not particularly limited, but it is preferably about 400 mgKOH/g or less, typically 300 mgKOH/g or less, for example, 250 mgKOH/g or less for commercial product specifications. Thereby, it is easy to finely adjust the amount X of the acid value per unit mass of the paste. In addition, excessive increase in affinity with the inorganic component (A) in the paste can be suppressed. Therefore, the increase in the viscosity of the paste can be suppressed, and the handleability of the paste and the workability at the time of film formation can be improved. Furthermore, self-leveling property can be improved, and the conductor film of smooth surface can be realized suitably.

In addition, the rosin-type resin (B-2) may contain the acid-value-free rosin which does not have an acid value other than the acid value rosin which has an acid value. The acid-value-free rosin refers to a rosin-based resin having an acid value below the detection lower limit (depending on the measurement accuracy, but approximately 0.5 mgKOH/g or below). When the acid-value-free rosin is contained, the ratio of the acid-value-free rosin to the entire rosin-based resin (B-2) is not particularly limited, but it is preferably less than 50% by mass, for example, 10% by mass or less.

The content ratio of the rosin-based resin (B-2) is not particularly limited, but it is approximately 0.1 to 10% by mass, typically 0.5% by mass when the entire paste is 100% by mass. ~5% by mass, such as 3% by mass or less, preferably 2% by mass or less, more preferably 1% by mass or less. When the ratio of rosin-type resin (B-2) is more than predetermined value, the technical effect disclosed here can be exhibited stably and more favorably. When the ratio of the rosin-based resin (B-2) is equal to or less than a predetermined value, a highly conductive and dense electrode layer can be suitably realized. In addition, the workability of the paste and the workability at the time of film formation can be improved, and the occurrence of delamination can be suppressed to a high degree.

It should be noted that the organic component (B) may be composed of an organic binder (B-1) and a rosin-based resin (B-2), or may be in addition to the organic binder (B-1) and a rosin-based resin (B-2) ) and various organic additives as needed. As the organic additive, known organic additives that can be used in common conductive pastes can be appropriately used as long as the technical effect disclosed here is not significantly impaired. Examples of organic additives include organic solvents (B-3), dispersants (B-4), leveling agents, defoamers, thickeners, plasticizers (B-5), pH regulators, Stabilizers, antioxidants, preservatives, colorants (pigments, dyes, etc.), etc.

<(B-3) Organic solvent>

The organic solvent (B-3) is a component for dispersing the inorganic component (A), for example, the conductive powder (A-1) and the dielectric powder (A-2). In addition, it is also a component that imparts appropriate viscosity and fluidity to the paste, thereby improving the handling properties of the paste and the workability at the time of film formation. The type and the like of the organic solvent (B-3) are not particularly limited, and one or two or more kinds of organic solvents generally used can be used appropriately depending on the application or the like. From the standpoint of improving workability during film formation and storage stability of the paste, a high-boiling organic solvent with a boiling point of approximately 200°C or higher, for example, 200 to 300°C, is the main component (accounting for 50% by volume) The above ingredients) are appropriate.

A preferred example of the organic solvent (B-3) includes alcohol-based solvents having -OH groups such as terpineol, Texanol, dihydroterpineol, and benzyl alcohol; binary solvents such as ethylene glycol and diethylene glycol; Alcohol-based solvents; diethylene glycol monoethyl ether, butyl carbitol (diethylene glycol monobutyl ether) and other glycol ether-based solvents; isobornyl acetate, diethylene glycol monoethyl ether Ester, Ethylene Glycol Monobutyl Ether Acetate, Diethylene Glycol Monobutyl Ether Acetate, Butyl Cellosolve Acetate, Butyl Carbitol Acetate (Diethylene Glycol Monobutyl Ether B Ester-based solvents with ester bond groups (R-C(=O)-O-R') such as acid esters); hydrocarbon-based solvents such as toluene and xylene; mineral spirits, etc. Among them, alcohol-based solvents can be preferably used.

When the paste contains the organic solvent (B-3), the content ratio of the organic solvent (B-3) is not particularly limited, but when the whole paste is 100% by mass, it is approximately 70% by mass or less, typically It is preferably 5 to 60% by mass, for example, 30 to 50% by mass. By satisfying the above-mentioned range, appropriate fluidity can be imparted to the paste, and workability at the time of film formation can be improved. In addition, the self-leveling property of the paste can be improved to realize a conductor film with a smoother surface.

<(B-4) Dispersant>

Dispersant (B-4) uniformly disperses inorganic component (A), typically conductive powder (A-1) and dielectric powder (A-2) in the paste, and highly inhibits inorganic component (A) Particle aggregates. In addition, in this specification, a "dispersant" refers to all amphiphilic compounds having a hydrophilic part and a lipophilic part, and is a term that also includes so-called surfactants, wetting and dispersing agents, and emulsifiers. However, for rosin and its derivatives, even amphiphilic compounds with acidic groups, It is classified into the above-mentioned rosin-based resin (B-2).

The dispersant (B-4) is not particularly limited, and one or two or more kinds of dispersants generally used can be used appropriately depending on the application. A preferred example of the dispersant (B-4) includes a carboxylic acid-based dispersant having a carboxyl group (COO ^- group), a phosphoric acid-based dispersant having a phosphonic acid group (PO ₃ -group, PO ₃ ^{2- group} ) Anionic dispersants with acidic groups, such as sulfonic acid-based dispersants with sulfonic acid groups (SO ₃ -group, SO ₃ ^{2- yl} ), cationic dispersants with amino groups, etc. Among them, it is preferable to use a carboxylic acid-based dispersant having a weak acidity in consideration of the use in combination with the rosin-based resin (B-2). By using a carboxylic acid-based dispersant, a relatively larger amount of rosin-based resin (B-2) can be used than, for example, other anionic dispersants, and the technical effects disclosed here can be exhibited at a higher level .

When the dispersant (B-4) is contained in the paste, the content ratio of the dispersant (B-4) is not particularly limited, but when the whole paste is 100% by mass, it is about 0.01 to 5% by mass, typically More specifically, it is preferably 0.05 to 3% by mass, for example, 0.1 to 2% by mass. By satisfying the above-mentioned range, the effect of the addition of the dispersant can be appropriately exerted to improve the uniformity, dispersibility, and storage stability of the paste, and to achieve better conductivity and a dense electrode layer.

<(B-5) Plasticizer>

The plasticizer (B-5) is a component that imparts flexibility to the conductor film or improves the toughness of the conductor film. The plasticizer (B-5) is not particularly limited, and one or two or more kinds of plasticizers generally used can be used appropriately depending on the application or the like. As a preferred example of the plasticizer (B-5), dibutyl phthalate, dibutyl phthalate, Octyl, diisononyl phthalate, diisodecyl phthalate, dioctyl terephthalate and other phthalates; dioctyl adipate, diisononyl adipate and other adipic di Esters; trimellitates such as trioctyl trimellitate; phosphates such as tricresyl phosphate; citrates such as acetyl tributyl citrate; sebacate; maleate; benzoate esters; epoxidized vegetable oils such as epoxidized soybean oil and epoxidized linseed oil; acrylic monomers such as acrylates such as acrylic acid and methyl acrylate; Low-molecular-weight polyesters of diols; etc.

When the paste contains the plasticizer (B-5), the content ratio of the plasticizer (B-5) is not particularly limited, but when the whole paste is 100% by mass, it is approximately 0.01 to 5% by mass, Typically, it is preferably 0.05 to 3% by mass, for example, 0.1 to 2% by mass. By satisfying the above-mentioned range, the effect of plasticizer addition can be exhibited suitably, the flexibility (bending resistance) and toughness of a conductor film can be improved, and ductility can be suppressed low. Therefore, even when stress is applied to the conductor film by, for example, pressurization, cutting, etc., deformation of the conductor film can be suppressed. In addition, an electrode layer with high conductivity and high density can be realized more favorably.

(X/Y)。通過滿足上述比(X/Y)，松香系樹脂的酸性基團適當地作用於無機成分的表面，而良好地發揮松香系樹脂的作為增黏劑的效果。上述比(X/Y)大致為1.0以上、一例中為1.2以上、例如1.8以上為宜。需要說明的是，上述X的值通過上述 的式(1)求出。另外，上述Y的值通過上述的式(2)求出。 In the paste disclosed here, when the acid value amount of rosin having an acid value per unit mass of the paste is X (mgKOH), and the content of inorganic components per unit mass of the paste is Y (g), there is an acid value. The ratio (X/Y) of the acid value X of the rosin to the content Y of the inorganic component satisfies the following formula: 0.8

(X/Y). By satisfying the above ratio (X/Y), the acidic group of the rosin-based resin acts appropriately on the surface of the inorganic component, and the effect of the rosin-based resin as a tackifier is exhibited favorably. The above-mentioned ratio (X/Y) is generally 1.0 or more, in one example, 1.2 or more, for example, 1.8 or more. In addition, the value of the said X is calculated|required by the said Formula (1). In addition, the value of Y mentioned above is calculated|required by the above-mentioned formula (2).

3。根據本發明人等的研究，若上述比(X/Y)增大則存在導體膜的表面粗糙度Ra增大的傾向。例如具有多層疊結構的層疊陶瓷電子部件中，導體膜的表面的稍微的凹凸導致層疊結構的形變，有可能成為短路不良等不良問題。因此，在這種用途中，優選滿足上述比(X/Y)。通過上述比(X/Y)為規定值以下，可以更良好地提高導體膜的表面平滑性，例如可以將導體膜的表面粗糙度Ra抑制得小、直至5nm以下。從上述觀點考慮，上述比(X/Y)大致為2.83以下、優選2.7以下、更優選2.6以下為宜。 The upper limit of the above-mentioned ratio (X/Y) is not particularly limited, but is preferably approximately 7.0 or less, in one example 5.0 or less, for example 4.5 or less. In a preferred example, the above ratio (X/Y) satisfies the following formula: (X/Y)

3. According to studies by the inventors of the present invention, as the ratio (X/Y) increases, the surface roughness Ra of the conductor film tends to increase. For example, in a laminated ceramic electronic component having a multilayer structure, slight unevenness on the surface of the conductor film may cause deformation of the laminated structure, which may cause problems such as short circuit failure. Therefore, in such use, it is preferable to satisfy the above-mentioned ratio (X/Y). When the ratio (X/Y) is equal to or less than a predetermined value, the surface smoothness of the conductor film can be improved more favorably, for example, the surface roughness Ra of the conductor film can be suppressed down to 5 nm or less. From the above viewpoint, the ratio (X/Y) is preferably approximately 2.83 or less, preferably 2.7 or less, more preferably 2.6 or less.

The value of the aforementioned X is not particularly limited. For example, about 30 mgKOH or more, in one example, 40 mgKOH or more, for example, 45 mgKOH or more, and about 500 mgKOH or less, in one example, 300 mgKOH or less, for example, 250 mgKOH or less, per 100 g of the paste.

Moreover, the value of said Y is not specifically limited, either. For example, about 30 g or more, in one example, 40 g or more, for example, 50 g or more, and about 95 g or less, in one example, 70 g or less, for example, 65 g or less, per 100 g of the paste.

Such a paste can be produced by weighing the above-mentioned materials at a predetermined content ratio (mass ratio), and uniformly stirring and mixing them. Stirring and mixing of the materials can be performed using conventionally known various stirring and mixing devices, such as an open mill, a magnetic stirrer, a planetary mixer, a disperser, and the like. In addition, for applying the paste to the substrate, for example, screen printing can be used. Printing methods such as brush, gravure printing, offset printing, and inkjet printing, spray coating methods, etc. In particular, the gravure printing method capable of high-speed printing is preferable for the application of forming an internal electrode layer of a laminated ceramic electronic component.

According to the conductive paste disclosed herein, for example, a conductive film having an elastic modulus E of 0.1 to 3.0 (GPa) in dynamic elastic modulus measurement (DMA) at 70° C. can be formed. Thereby, the adhesiveness and wettability of a conductor film can be improved, and ductility can be suppressed low. Therefore, even when stress is applied to the conductor film by, for example, pressurization, cutting, etc., deformation of the conductor film can be suppressed.

As described above, according to the conductive paste disclosed herein, it is possible to form a conductive film having excellent adhesion to a base material. For example, in the 180° peeling test performed by the method described in the examples described later, the peeling strength (peeling strength) to the substrate (ceramic green sheet) can be 150 gf/cm or more, preferably 180 gf/cm or more, more preferably 190 gf /cm or more, more preferably 200 gf/cm or more, and for example, a conductor film of 300 gf/cm or less. Such a conductive film having a high peel strength can properly maintain the integrity with the base material even when stress is applied to the conductive film by, for example, pressurization or cutting.

<Use of the paste>

Typical applications of the paste disclosed herein include formation of internal electrode layers in laminated ceramic electronic components. The paste disclosed here can be suitably used for forming an internal electrode layer of an ultra-small MLCC having a side of 5 mm or less, for example, 1 mm or less, for example. It should be noted that, in this specification, "ceramic electronic component" refers to a general amorphous ceramic base material (glass ceramic base material) or crystalline material (i.e. A term for electronic components based on ceramic substrates other than glass). For example, inductors, high-frequency filters, actuators, ceramic capacitors, low-temperature fired laminated ceramic substrates (Low Temperature Co-fired Ceramics Substrate: LTCC substrates), high-temperature fired A laminated ceramic substrate (High Temperature Co-fired Ceramics Substrate: HTCC substrate) and the like are typical examples included in the "ceramic electronic component" referred to here.

Examples of ceramic materials constituting the ceramic substrate include barium titanate (BaTiO ₃ ), zirconia (zirconia: ZrO ₂ ), magnesium oxide (magnesia: MgO), alumina (alumina: Al ₂ O ₃ ), oxide Silicon (silicon dioxide: SiO ₂ ), zinc oxide (ZnO), titanium oxide (titanium dioxide: TiO ₂ ), cerium oxide (cerium oxide: CeO ₂ ), yttrium oxide (yttrium trioxide: Y ₂ O ₃ ), etc. Oxide materials; cordierite (2MgO.2Al ₂ O ₃ .5SiO ₂ ), mullite (3Al ₂ O ₃ .2SiO ₂ ), forsterite (2MgO.SiO ₂ ), steatite (MgO.SiO ₂ ), sialon (Si ₃ N ₄ -AlN-Al ₂ O ₃ ), zircon (ZrO ₂ .SiO ₂ ), ferrite (M ₂ O.Fe ₂ O ₃ ) and other composite oxide materials ; Silicon nitride (silicon nitride: Si ₃ N ₄ ), aluminum nitride (aluminum nitride: AlN) and other nitride-based materials; silicon carbide (silicon carbide: SiC) and other carbide-based materials; Phyto-based materials; element-based materials such as carbon (C) and silicon (Si); or inorganic composite materials containing two or more of them; etc.

FIG. 1 is a cross-sectional view schematically showing a multilayer ceramic capacitor (MLCC) 10 . The MLCC 10 is a ceramic capacitor in which a plurality of layers of dielectric layers 20 and internal electrode layers 30 are alternately stacked. Dielectric layer 20 is made of, for example, ceramics. The internal electrode layer 30 is composed of a baked body of the conductive paste disclosed herein. MLCC10 for example through the following steps of manufacture.

That is, first, a ceramic green sheet as a base material is prepared. In one example, a ceramic material as a dielectric material, a binder, an organic solvent, and the like are stirred and mixed to prepare a paste for forming a dielectric layer. Next, the prepared paste is spread on a carrier sheet by a doctor blade method or the like to form a plurality of unfired ceramic green sheets. The ceramic green sheet is the portion that forms the dielectric layer after firing.

Next, the conductive paste disclosed here is prepared. Specifically, at least conductive powder (A-1), organic binder (B-1) and rosin (B-2) are prepared, and they are stirred and mixed so that the above ratio (X/Y) is satisfied to produce a conductive powder (A-1). paste. Next, the prepared paste is applied in a predetermined pattern and with a desired thickness (for example, submicron to micron level) on the plurality of ceramic green sheets formed above to form conductor films respectively. This conductive film is a portion where the internal electrode layer is formed after firing.

After producing a plurality of unfired ceramic green sheets with a conductive film (for example, hundreds to thousands of sheets), they are laminated and bonded by pressure. Thus, an unfired laminated wafer was produced.

Next, the unfired laminated wafer prepared above is cut into a desired size, and then fired under appropriate heating conditions (for example, a temperature of about 1000 to 1300° C.). In this way, the laminated wafers are simultaneously fired (baked) and integrally sintered. As described above, a composite body in which a plurality of layers of dielectric layers 20 and internal electrode layers 30 are alternately stacked can be obtained. Then, finally, electrode materials are coated on both end surfaces of the fired composite body and baked. Thus, the external electrodes 40 are formed. MLCC10 can be manufactured as above.

Some examples of the present invention will be described below, but the present invention is not intended to be limited to the above examples.

<Manufacture of conductive paste>

First, as shown in Table 1, conductive powder (A-1) and dielectric powder (A-2) as inorganic components, and organic binder (B-1) and rosin-based resin (B-2) as organic components were prepared. , an organic solvent (B-3), a dispersant (B-4) and a plasticizer (B-5) were mixed to manufacture conductive pastes (Examples 1-14, Comparative Examples 1-7). In addition, the manufacturer's nominal value (the value measured by the potentiometric titration method based on JISK0070:1992) is described about the acid value of a rosin-type resin. In addition, as the conductive powder (A-1), nickel powder having an average particle diameter (nominal value of the manufacturer; average particle diameter based on the number of electron microscope observations) of 0.25 μm and a specific surface area of 2.75 m ² /g was used . In addition, as the dielectric powder (A-2), titanium with an average particle diameter (nominal value of the manufacturer; average particle diameter based on the number of electron microscope observations) of 0.05 μm (50 nm) and a specific surface area of 21 m ² /g was used. Barium Oxide Powder.

<Calculation of ratio (X/Y)>

Next, the value of the above-mentioned ratio (X/Y) is calculated using the above-mentioned formula (1) and formula (2).

Specifically, first, for each example, the acid value X (mgKOH) of the rosin-based resin in 100 g of the paste was calculated from the acid value (mgKOH/g) of the rosin-based resin×the content ratio (mass %). Next, for each example, the content ratio (mass %) of the conductive powder and the content ratio (mass %) of the dielectric powder were summed up to calculate the content Y (g-inorganic component) of the inorganic component in 100 g of the paste. Next, the acid value X of the rosin-based resin in 100 g of the paste was divided by the content Y of the inorganic component in 100 g of the paste to calculate the ratio (X/Y). The results are shown in Table 1.

<Measurement of Peel Strength>

First, a base material in which a ceramic green sheet is attached to the surface of a polyethylene terephthalate (PET) film is prepared. Then, the above-mentioned conductive paste was coated on the surface of the ceramic green sheet side of the above-mentioned substrate by screen printing in a rectangular pattern of 35mm×22mm, and the temperature was 80°C. 5 minutes of hot air drying. Thus, a conductor film having a thickness of about 1 µm was formed on the ceramic green sheet.

Then place the second ceramic green sheet on the conductor film formed above, and conduct 70°C. 6 seconds of thermocompression bonding. After leaving this to stand in an environment of 25° C. for 30 minutes, the PET film was peeled off to obtain a laminate in which ceramic green sheets were crimped on both surfaces of the conductor film. Next, this laminated body was cut|disconnected so that the conductor film may become a size of 5 mm x 32 mm. Next, one side of the ceramic green sheet is fixed on the alumina substrate with a double-sided adhesive tape, and a double-folded scotch tape is attached to the other side of the ceramic green sheet. Next, using a tensile tester, the two ceramic green sheets were stretched in opposite directions under tensile conditions: tensile speed: 100 mm/min, peeling angle: 180°, and the conductor film and the ceramic green sheet were peeled off. From the average load at this time, the peel strength of the conductor film (for the ceramic green sheet, unit: gf/cm width) was obtained.

The results are shown in Table 1. It should be noted that the larger the value of the peel strength, the better the bonding property. In Table 1, when the peel strength value was 180 gf/cm or more, it was judged that the adhesiveness was good, and "◯" was shown. On the other hand, when the adhesiveness was less than 180 gf/cm, it was judged that the adhesiveness was insufficient, and "x" was shown.

<Measurement of Surface Roughness>

Using an optical interference microscope, the surface smoothness (arithmetic mean roughness Ra) of the conductor film was calculated under the following conditions.

Device: Non-contact 3D surface shape measurement system with super-resolution capability BW-A501 (manufactured by Nikon Corporation)

Optical microscope LV-150 (manufactured by Nikon Corporation)

Magnification: 100 times, operating width: ±5μm, measurement range: 50μm×1000μm

The results are shown in Table 1. It should be noted that the smaller the value of Ra, the better the surface smoothness. In Table 1, when the value of Ra was less than 5 nm, it was judged that the surface smoothness was good, and "◯" was shown. On the other hand, when the value of Ra was 5 nm or more, it was judged that the surface smoothness was insufficient, and "x" was shown. In addition, "-" means not measured.

Fig. 2 is a graph showing the relationship between X/Y and peel strength. As shown in Table 1 and FIG. 2 , in Comparative Example 1 in which neither the rosin-based resin nor the plasticizer was added, the peel strength was the smallest. On the other hand, in Comparative Examples 2 and 3 in which only the plasticizer was added at a ratio of 1.5 to 2% by mass, a slight increase in adhesiveness was observed. In addition, in Comparative Examples 4 to 7 in which the ratio (X/Y) of the acid value amount X of the rosin-based resin to the content Y of the inorganic component was 0.12 to 0.4, it was found that the adhesiveness increased as X/Y increased. tendency. On the other hand, in Examples 1 to 14 in which X/Y satisfies 0.8 or more (here, 0.8 to 4.14), the peel strength of the conductor film increased to 195 gf/cm or more, and a significant increase in adhesiveness was achieved.

As can be seen from the above, according to the conductive paste disclosed here, compared with, for example, Comparative Examples 1 to 7, which do not contain a rosin-based resin or have a small X/Y, it is possible to form an improved adhesiveness to the substrate. conductive film.

In addition, as shown in Table 1, in Examples 8, 10, and 14 in which X/Y is large, the unevenness of the surface of the conductor film is large. In contrast, in Examples 1 to 7, 9, and 11 to 13 in which X/Y satisfies 3 or less (2.83 or less), the surface roughness Ra of the conductor film was suppressed to 5 nm or less, and excellent surface smoothness was achieved .

From the above, it can be seen that when X/Y is 3 or less, more preferably 2.6 or less, a conductive film having excellent surface smoothness can be formed compared with a conductive paste having a large X/Y.

As mentioned above, although this invention was demonstrated in detail, these are only an illustration, and various changes can be added to this invention in the range which does not deviate from the summary.

Claims (7)

A conductive paste containing an inorganic component and an organic component for forming a conductive film, the inorganic component contains conductive powder, the organic component contains an organic binder and a rosin-based resin, and the rosin-based resin contains Acid-value rosin with an acid value, the amount of acid value per unit mass of the acid-value rosin of the conductive paste is set to X, and the content of the inorganic component per unit mass of the conductive paste is When set to Y, said X and said Y satisfy the following formula: 0.8

(X/Y)

2.83, wherein the unit of X is mgKOH, and the unit of Y is g, wherein when the whole of the conductive paste is taken as 100% by mass, the content ratio of the conductive powder is 30% by mass or more, and the organic binder The content ratio of the rosin-based resin is 0.1 to 10% by mass, and the content ratio of the rosin-based resin is 0.1 to 10% by mass. The conductive paste according to claim 1, wherein the acid value of the rosin having an acid value is 100 mgKOH/g or more. The conductive paste according to claim 1, wherein the rosin-based resin is 2% by mass or less when the entirety of the conductive paste is 100% by mass. The conductive paste as described in claim 1 of the patent application, wherein the conductive powder is at least one of nickel, platinum, palladium, silver and copper. The conductive paste according to claim 1, wherein the inorganic component further contains dielectric powder. The conductive paste according to claim 1, which is used for forming an internal electrode layer of a laminated ceramic electronic component. A method of manufacturing a ceramic electronic component, which includes the step of forming an electrode layer by applying the conductive paste according to any one of claims 1 to 6 to a ceramic green sheet and then firing it.

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